Objective: To better understand how heterogeneity in attention-deficit hyperactivity disorder (ADHD) symptoms relates to heterogeneity in functional impairment domains in children with ADHD after accounting for demographic variables and comorbidities, in particular oppositionality and internalizing symptoms.
Methods: Parents and teachers (n = 5663) rated child/adolescent impairments across impairment domains in the International Classification of Functioning, Disability and Health as well as symptoms of ADHD and comorbidities. Hierarchical regressions were conducted to assess the relationship between parent and teacher ratings of ADHD symptom domains and functional impairments after accounting for personal factors and comorbid disorders.
Results: Symptoms of inattention were the strongest predictors of ratings of academic (math, writing, and so on) functioning, while hyperactivity/impulsivity symptoms were the strongest predictor of classroom disruption even after accounting for the presence of learning disorders and oppositional symptoms. Symptoms of ADHD accounted for minimal variance in interpersonal functioning or participation in organized activities after controlling oppositional symptoms.
Conclusion: The ADHD symptom domains demonstrate domain-specific relations with various ADHD-related functional impairments. In addition, the results highlight the role of oppositionality in interpersonal relationship difficulties and participation in organized activities.